Comminuted ore feed control



Oct. 23, 1956 J. H. CARPENTER COFAMINUTED ORE FEED CONTROL 7 Filed Nov. 15, 1952 3 Sheets-Sheet l 1/ 1/0722, ub/7 65 Ha/l Uqrpgsnfer,

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Oct. 23, 1956 J. H. CARPENTER COMMINUTED ORE FEED CONTROL 3 Sheets-Sheet 2 Filed Nov. 15. 1952 fm/enl'or 0765 Hall Carp enfer,

cfa g b 16. J4; i475 Oct. 23, 1956 J. H. CARPENTER 2,767,844

COMMINUTED ORE FEED CONTROL Filed Nov. 15. 1952 3 Shets-Sheet 3 is fl fforqgy.

2,767,844 Patented Oct. 23, 1956 United States Patent Dfiice 2,767,844 COMMINUTED ORE FEED CONTROL James Hall Carpenter, Jacksonville, Fla. Application November 15, 1952, Serial No. 320,790 9 Claims. c1. 209- 231 My invention relates to comminuted ore feed control and particularly relates to devices for controlling the rate of flow of comminuted ore from a supply bin in a thin sheet. Accordingly, the arrangements contemplated in my invention are particularly adapted for feeding comminuted ore in ore separating systems utilizing elongated horizontal rolls, belts or the like and in which it is necessary to supply a relatively smooth or even blanket or sheet of ore from a hopper across the roll surface.

A general object of my invention is to provide an improved control to regulate the rate of flow of comminuted ore to an ore treatment member or device.

A further object of my invention is to provide an ore feeding system which will supply a steady flow of ore evenly across an elongated horizontal lip at an adjustable rate of flow.

A more specific object of my invention is to provide a control for regulating the rate of flow of comminuted ore, the control being manually or automatically operable conveniently, rapidly and positively into a position to interrupt the flow without danger of clogging, sticking or similar malfunctioning.

An additional object of my invention is to provide a flow-regulating mechanism for 'comminuted ore which is subject to a minimum of such wear as would alter the flow or require frequent replacement of parts.

An additional specific object of my invention is to provide flow regulating means embodying adjustable members which may be set and arranged to compensate for slight warping or misalignment of the portions controlling the ore flow.

A specific object of my invention is to provide a control for regulating the flow of ore in a separator of the magnetic type wherein the flow is automatically interrupted upon de-energization of the magnets.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is a perspective view of an ore feeding arrangement .in accord with my invention as embodied in an induced roll magnetic ore separator, a portion of the control mechanism being shown for clarity in exploded position;

Fig. 2 is a side view, on an enlarged scale, of portions of the machine of Fig. 1 showing further details of the ore feeding and control arrangement; I

Fig. 2A is an enlarged detail side view of a portion of the machine of Fig. 2 demonstrating the action of the flow control arrangement;

Fig. 3 is a sectional view of a portion of the control mechanism of Fig. 2, the mechanism being in condition to interrupt the flow of ore to the roll;

Fig. 4 .is a side view of a portion of an electrostatic ore separating machine embodying a control mechanism in accord with my invention, the mechanism being modified from that of Figs. l-3 to adapt it particularly to an elec trostatic machine;

Fig. 5 is a detail of a of Fig. 4 in condition to of the machine;

Fig. 6 is a front view of a portion of the control mechanism and machine of Fig. '4;

Fig. 7 is a detail view of a portion of the control arrangement taken along line 77 of Fig. 6; and

Fig. 8 is a sectional view taken along line 8-8 of Fig. 4 and disclosing an arragement for adjusting the evenness of How across the roll supply lip from side to side of the machine.

' Fig. 1 of the drawings shows a portion of an induced roll magnetic ore separating machine of the general type disclosed in my application for United States Letters Patent, Serial No. 241,283, filed August 10, 1951, and entitled Magnetic Induced Roll Ore Separator, embodying, however, an improved ore feeding arrangement in acportion of the control mechanism shut off the flow of ore to the roll cord with the present invention. The machine comprises basically an ore particle receiving member in the form' of a magnetic roll 1 arranged between pole pieces 2 and 3, the pole pieces being adapted for excitation by electromagnetic coils 4. netic metal, such as aluminum, is arranged within the magnetic core structure, and comminuted ore particles may be supplied through conduits 6 from any desired source into bin 5. Conduits 6 are preferably non-magnetic and extend through the core structure. The bin 5 has a slotted or open ore'feeding lower portion through which ore slides onto a non-magnetic bottom p-late'7, the plate 7 being effectively an extension of the back lower wall of bin 5. Ore from the pile on'plate 7 normally cascades or falls in a sheet or blanket over an upwardly ex tending lip Sunder the control of blade 9 onto an upper surface of the ore treatment roll 1. Blade 9 conveniently comprises an elongated angle member which extends from side to side of the machine and which is afiixed to, and supported by, a shaft 10. A hearing for shaft 10 is supplied in a side plate. 11 at one side of the machine, and, while shaft 10 may extend completely across the machine andmay have a bearing in end plate 12 at the far side, Fig. l of the drawing indicates that 'a short shaft 10 engages only one end of the blade member 9 and that a similar short shaft 13 is attached to and supports the other end of'member 9. Thu shaft 13 would be journalled in side plate 12 at thefar side of the machine.

Rotation of shaft 10 serves to raise or lower the lower edge 14 of control blade 9, and regulation of the rate of flow of ore in the blanket cascading over lip 8 is obtained by adjusting the position of edge 14 by rotating :energization to the shaft 10. The mechanism for adjusting the position of edge 14 i disposed against the outer surface of side plate 11 andcompn'ses a sector 15 rigidly afiixed, as by a set screw 16, to shaft 10 and an arm 17 rotatably mounted on shaft 10. Arm 17 may be clamped to sector 15 in desired relation thereto by means of a locking bolt and wing nut 18, the bolt being afiixedto arm 17 and extending through arcuate aperture 19 formed in sector 15. A magnetic keeper member 20 is attached for magnetic core structure of the machine, and when the machine core is energized, and the knob '21, which is of magnetic material, is brought into contact with keeper 20, arm 17 is retained in the position indicated in Fig. l. Tension spring 22, which is fixed to plate 11-by a post 23, urges or biases arm 17 for clockwise rov stantially reduced, however, the magnetic attraction of;

tation, as. seen in Fig. 1, since the lower end of tension A supply hopper or bin 5 of non-m-ag-' 3 keeper 20 for steel knob 21 is reduced, and .if the reduction is sufiicient, spring 22 causes arm 17 to rotate, about the axis of shaft 10, until the arm engages a stop 25. Since in normal operation sector 15 is clamped to arm 17 by bolt and wing nut 18, the rotation of arm 17 toward stop 25 carries sector 15 with it and rotates shaft and blade 9 in a clockwise direction, as seen .in Fig. 1. As will be more fully explained hereinafter, clockwise rotation of shaft 10 and the resultant lowering of edge 14 of blade 9 into the pile or heap of ore behind the lip will, if the edge is sufliciently lowered, serve to cut off the flow of ore to the upper surface of roll 1. The feeding atrangement of my invention, accordingly, as applied to the magnetic induced roll machine, operates automatically to stop the flow of ore in the event of failure of the power source supplying magnet coils 4.

it will be understood by those skilled in the art that as many as possible of the parts of a magnetic separator should be made of non-magnetic materials, with the exception, of course, of the magnetic core and roll. Accordingly, the frame 26, splitter bar 27, bin 5, side plates 11 and 12, and the sector and arm 17 of the control mechanism, may all be of non-magnetic materials. Control blade member 8 may be non-magnetic, although it has been found that a steel blade is satisfactory and less subject to wear than blades formed of any common nonmagnetic material. As previously mentioned, keeper and knob 21 are both of steel to provide the automatic operation of the control mechanism.

Fig. 2 is a side view of the lower portion of the machine of Fig. l disclosing details of the control arrangement. The lower corner of side plate 11 has been broken away to show blade member 9 in operative position with its lower edge 14 at a position such that ore particles 28 will flow or cascade in a thin sheet or blanket over the lip 8 of bottom plate 7. The angle of rest of comminuted ore particles of the type particularly appropriate for separation by induced roll separators is usually between about and degrees from the horizontal. Thus, as seen in Fig. 2, and in further enlarged detail in Fig. 2A, particles flowing under edge 14 will have an upper surface inclined downwardly toward the right from edge 14, which surface will be substantially at the angle of rest of the particular materials. The thickness of the sheet of ore particles passing over lip 8, accordingly, is determined by the distance between the upper edge of lip 8 and a plane corresponding to the angle of rest of the material, the line extending at such angle from the edge 14. Accordingly, the rate of fiow of the ore particles may be adjusted by changing the position of edge 14, and the control mechanism shown accomplishes such adjustments by appropriate rotative positioning of shaft 10. Since sector 15 is attached to shaft 10, the desired adjustment may be made by moving the sector. In aocomplishing the desired adjustment, the machine may be energized and the wing nut 18 may be loosened. Knob 21 of arm 17 is brought into contact with magnetic keeper 20 and is there held by the attraction of the keeper. The sector may now be adjusted to provide the desired rate of flow of particles over lip 8, and when the correct rate is established. wing nut 18 is tightened to lock sector 15 to arm 17. The flow continues at the adjusted rate thereafter until further rotation of sector 15 is accomplished. Such further movement of sector 15 can be the result of further adjustments, wing nut 18 having been loosened again for this purpose, or such motion may occur as a result of the rotation of arm 17 toward stop 25. For example, knob 21 may be manually pushed from contact with keeper 20 if the operator wishes to stop the flow for any reason, or the arm may move as a result of demagnetization of keeper 20 due to power failure. When the attraction of keeper 20 for knob 21 is sufficiently reduced, tension spring 22 through its attachment to arm 17 forces the arm, and with it sector 15 and blade 9,

to rotate in a clockwise direction. Such rotation of arm 17 into contact with stop 25 results in the lowering of edge 14 into the position indicated in Fig. 3. The angle of rest below edge 14 in the position of Fig. 3 intersects lip 8 slightly below its upper edge and the fiow of ore over lip 8 immediately and completely stops. The amount of ore in bin 5 has no appreciable effect upon the rate of flow as determined by the blade position during normal operation as exemplified in Fig. 2, nor does it effeet the completeness of the termination of flow when the blade 9 is positioned as shown in Fig. 3. Ore from the bin 5 is prevented from flowing over the top of blade 9 or shaft 10 by the location of edge 29 which defines the upper boundary of the bottom ore feeding slot of bin 5. The surface at the angle of rest of material from edge 29 passes below the uppermost portions of blade 9 and shaft 10. However, substantially the whole space to the left of blade 9 may fill with ore particles.

It will be noted from the above description, and from a study of the drawings, that lower edge 14 of blade 9 in normal feeding position is spaced from lip 8 and from plate 7 by a substantial distance in each case, the distances being several times as great as the thickness of the sheet of ore particles which pass over lip 8. Furthermore, the stream of ore over lip 8 may be completely and positively cut off merely by moving edge 14 downwardly into the pile of ore particles behind the lip, and it is not necessary that the edge 14 meet bottom plate 7, lip 8, or any other solid member at any time. No ore particles, accordingly, can become wedged in a position to interfere with the flow or to interfere with movement of the control blade in either direction, and, because blade 9 is never forced into engagement with any other solid part, the wear on blade 9 is minimized.

Figs. l-3 described above relate particularly to an ore feeding arrangement applicable to an induced roll magnetic ore separator. Figs. 48 disclose an ore feed arrangement particularly adapted for use in an electrostatic roll type of comminuted ore separator, the type being exemplified in my prior U. S. Patent No. 2,548,771. An electrostatic separator of this type may comprise an ore treatment roll 30. It will be understood that a thin sheet or blanket may be treated by subjecting it, while on roll 30, to an electrostatic field. In accord with my invention, a sheet of comminuted ore is supplied by permitting the ore particles to cascade or fall in'a sheet over a lip 31 under the control of a blade 32, the lower edge 33 of the blade extending completely across the separating machine in substantially co-extensive and parallel relation to lip 31. Blade 32 is attached by bolts 34 to an angle member 35 which also extends from side to side of the machine. This arrangement of blade 32 permits slight adjustments to blade 32 to permit the lower edge 33 to be positioned substantially exactly parallel to lip 31, thereby to insure an evenness of flow of the ore particles from side to side of the machine. It will be seen that blade 32 and angle member 35 when attached together form a complete blade portion for controlling the ore flow.

. A supply bin or hopper 36 is arranged to receive a supply of ore to be treated, and the bin has a bottom ore feeding slot or opening between lower edges 37 and 38, respectively, of the back and front inclined lower walls of bin 36. Ore particles flowing through the opening collect in a pile on a plate 39 below the bin opening. and the ore pile is thus collected behind, that is, above and to the left of, lip 31 and behind blade assembly 32, 35. The upper surface of the ore collecting below the bin opening will assume the characteristic angle of rest. which may be about 30 to 35 degrees from the horizontal, and the ore surface will thus extend downwardly and toward the right from edge 38. This ore surface at the angle of rest would meet blade assembly 32, 35 at approximately the level of bolts 34. Ore flowing below lower edge 33 to cascade over lip 31 will remain below a plane extending toward the right and downwardly from edge 33 at the characteristic angle of rest of the ore particles. The rate of flow of ore cascading over. lip 31, accordingly, is controlled by the distance between the uppermost edge of lip 31 and the angle of rest determined by the position of blade edge 33. The position of blade edge 33 is under the control of a sector 40 rigidly afiixed to the end of a shaft 41, the shaft in turn being affixed to blade assembly 32, 35. As indicated in Fig. 4, side plate 42 .is bolted to bin 36 and angle member 35 extends from the inner surface of plate 42 across the machine to the inner surface of an opposite side plate adjacentthe opposite end of roll 30. Shaft 41 is journalled in plate 42 and extends outwardly from its outer face. Between sector 40 and the outer face of plate 42, an arm member 43 is mounted on shaft 41 in freely rotatable relation thereto. Arm 43 comprises a locking bolt and nut combination 44 which extends from arm 43 through an armate aperture 45 of sector 40. Thus arm 43 and sector 40 may be locked together in desired adjusted position. A latch-engaging post or stud extends toward plate 42 from arm 43 and this stud may be engaged within a notch 46 formed in the lower side edge of a latch bar 47. Notch 46 is so shaped as to retain arm 43 against" rotation in a clockwise direction, but latch bar 47'is pivotally mounted by a pintle 48 to plate 42 and the latchbar may be rotated in a counter-clockwise direction by manual downward force on a knob 49 to raise notch 46 sufficiently to disengage the post extending behind locking bolt 44. Such counter-clockwise rotation of bar 47 re-' leases arm 43 for rotation under the influence of tension spring 50. Spring 50 engages and supplies an upward force to an extension 51 of arm 43, and thus biases arm 43 for clockwise rotation. The upper end of spring 50 is attached to latch bar 47 to the right of pintle 48 to provide a clockwise bias to the latch bars In operation, the nut of locking combination44 may be loosened and, with the arm 43 retained in position with its post engaged in notch 46, which comprises the normal operating position for arm 43, sector 40 may be adjusted in position relative to the arm to rotate shaft 41 and angle member 35 into a desired position in which lower edge 33 of blade 32 is disposed at the position, in respect to lip 31, which permits ore to cascade over lip 31 at the desired rate. When the correct desired adjustment is obtained, the locking nut 44 is tightened to clamp arm 43 and sector 40 together.

With the feed arrangement set for desired operating flow rate, it may become necessary from time to time to interrupt the flow of ore. Such interruption can be rapidly accomplished by striking knob 49 so as to move it downwardly. The notch end of latch bar 47 is thereby raised against the bias of spring 50, and spring 50 immediately forces arm 43 to rotate in a clockwise direction, such as into engagement with a stop post 52. Such rotation results in a corresponding rotation of sector 40 and shaft 41 and, accordingly, results in downward motion of lower edge 33 toward plate 39 and further into the ore pile on plate 39. The positions of the members when the ore flow is thus interrupted are shown in Fig. 5. The downward motion of edge 33 places this edge sutficiently far behind lip 31, and at a low enough height with respect to lip 31, to be below the ore pile surface at the angle of rest which would be established by ore passing over lip 31 and, since ore cannot rise above its angle of rest be yond a blade interrupting its upper surface, the flow of ore over lip 31 is completely stopped.

To re-establish the original adjusted rate of flow of ore across lip 31, it is necessary only to grasp the knob 53 which is provided at the upper end of arm 43 and to move the arm in a counterclockwise direction from the position illustrated in Fig. 5 until latch notch 46 again engages over the rearwardly extending post of arm 43 in the position of Fig. 4. Furthermore, if an oversized pebble It will be understood that such motion of arm 43 to an extreme counterclockwise position should be momentary only, to prevent any extendedfiow of ore atthe greatly increased rate, but if knob 53 is moved to the left and immediately released, arm 43 snaps, under the influence of spring 50, back into normal operating position with its post engaged in notch 46, as seen in Fig. 4.

In the electrostatic machine of Fig. 4, means are provided to adjust the lip 31 to compensate for warping or uneven wear and to increase the rigidity of the ore feed ingportion of the machine. Such means comprise an angle member 54 bolted to the lower surface of plate 39 by means of bolts 55 in a manner hereinafter further explained in connection with Fig. 8. The smoothness and evenness of the flow of ore onto the upper surface of roll has been found to be improved by the further provi sion of an extending plate member 56 disposed below and'beyond lip 31 and approaching closely to the roll surface.

The several parts shown in detail in Fig.5, and further shown in Figs. 6, 7 and 8, are, in each case, identified by reference numerals corresponding to those of Fig. 4, and the description of Fig. 4 applies equally to the detail views of the portions of the machine shown in Figs. 5, 6, 7 and 8.

Referring particularly to Fig. 5, wherein the parts are arranged in flow stopping positions, it will be seen that spring 50 exerts an upward force on extension 51 of arm 43, retaining the arm against stop 52. The downward force of spring 50 on latch bar 47 forces the bar into engagement with stop 57, stop 57 being, like stop 52, a small post or stud extending outwardly from side plate 42. The position of sector 40 shown in Fig. 5 corresponds to the flow interrupting position of blade assembly 32, 35, and the control condition is. such that ore piled on plate 39 does not flow-over lip 31.

The front view of a portion of the machine shown in Fig. 6 discloses the latch bar 47 in position over post 58 to retain arm 43 in its upright, normal operating position,

. in accord with Fig. 4. As heretofore explained post 58 extends rearwardly from arm 43 and is permanently attached to the arm, while sector 40 is locked in desired position relative to arm 43 by means of locking combination 44. Spring 50 is seen to extend downwardly from latch bar 47 to a position behind hub 59 of arm 43 where the spring engages the hereinabove described extension of the arm. Knob 53 is attached to the upper end of arm 43 and knob 49 is mounted, as best seen in Fig. 4, to the far end of latch bar 47.

The arrangement by which shaft 41 is journalled in side plate 42 to support blade assembly 32, is readily seen in Fig. 6, and it will be noted that a pin 60 extends through the hub 61 of sector and through shaft 41 rigidly to afiix the sector to the shaft. Further details of the arrangement shown in Fig. 6 will be apparent from the above description of Fig. 4.

Fig. 7 is a sectional view taken along line 77 of Fig. 6 and disclosing the arrangement of sector 40, arm 43 and latch bar 47. Post 58, fixed to arm 43, when the machine is in the normal operating condition indicated in Fig. 4, is engaged in notch 46 of the latch bar, and the post is held in the notch 46 against shoulder 62 which bounds one end of the notch. Arm 43 is thus restrained by shoulder 62 against the bias of spring 50. The extension 51 from hub 59 of arm 43 serves to connect spring to the arm, and the upper end of the spring is seen to be connected to latch bar 47.

Fig. 8 is a sectional view taken along line 8-8 of Fig. 4 and showing in detail the arrangement of bolts for straightening plate 39. The upper flange 63 of reinforcing angle member 54 lies against or immediately adjacent the under surface of plate 39. Bolts 55 and 55' extend through flange 63 and are threaded into openings in plate 39. Bolts 55 and 55' are not threaded into flange 63, however, but pass through slightly oversized openings therein, and it will be apparent that tightening one or more of bolts 55 and 55 tends to pull flange 63 and plate 39 together at the position of the tightened bolt. Bolt 64, however, threads into flange 63 and bears against plate 39, whereby tightening of bolt 64 tends to separate plate 39 and flange 63. It is desirable that a number of bolts 55, threaded into plate 39, and an approximately equal number of bolts 64, threaded only into flange 63, should be provided across the length of angle member 54. If it is found that a particular section of lip 31 bows slightly upwardly, a bolt or bolts 55 adjacent the upwardly bowed portion should be tightened to urge plate 39 downwardly at this section. If, on the other hand, a section of lip 31 is bowed downwardly, permitting the flow of a blanket of increased thickness at that portion, the adjacent bolts 55 should be backed off slightly and the bolts 64 at that portion should be tightened to urge the adjacent section of plate 39 upwardly.

In electrostatic separating machines of the type illustrated, it is usually desired to provide a very thin sheet of ore in the cascade onto the roll, and the linearity adjustment for the lip 31 explained in connection with Fig. 8 is desirable in machines wherein a thin sheet of this nature is important. As heretofore explained, the arrangement of blade portion 32 which is slightly adjustable on angle member 35 of the blade assembly permits further adjustment to insure an even flow of ore particles across the length of lip 31. It will be understood that the openings in blade member 32 which pass bolts 34 are slightly oversize to permit adjustments of blade 32 on member 35. In magnetic induced roll separators, of the type shown in Figs. 1, 2 and 3, the sheet of ore supplied to the roll is, in the ordinary case, desirably somewhat thicker than in electrostatic separators, and it has been found that the fine adjustments provided by the adjustable blade arrangement 32, 35, and by the warping arrangement for plate 39 detailed in Fig. 8, are not necessary under ordinary circumstances in induced roll machines.

The magnetic separator of Fig. 1 inherently provides,

while the machine is properly energized, a magnetic field useful as an automatic holding force for the controlling arm of the flow control mechanism. While a magnetic field is not ordinarily conveniently available in an electrostatic separator, it will be apparent that electromagnetic means can be supplied in the latter type of machine to retain the operating arm in the manner described for the magnetic machine of Fig. 2. It will also be apparent that the latch bar arrangement shown in Fig. 4 could be provided instead of the magnetic keeper on an electromagnetic machine. Thus while the arrangement of Fig. 4 is particularly adapted to electrostatic machines, and the arrangement of Fig. l is particularly adapted to electromagnetic machines, the control system of the Fig. 1 type can be readily adapted to any machine wherein an electric current is available for energizing a magnetic keeper, and the control mechanism of the Fig. 4 type is readily adaptable for use if desired on electromagnetic machines. 3 While I have shown and described only certain preferred embodiments of my invention by way of illustration, many modifications will occur to those skilled in the art, and I therefore wish to have it understood that l' intend, in the appended claims, to cover all such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. Ore feeding means for supplying a continuous freely falling blanket of comminuted ore particles comprising, an elongated lip; means to heap ore particles to be treated behind said lip to a height necessary to cause particles to cascade over said lip, said means comprising ore delivery means behind and spaced from said lip; a control blade between said ore delivery means and said lips and spaced from said ore delivery means and from said lip; and adjusting means connected to said blade operative adjustably to position said blade into said heap; said adjusting means comprising a first member rigidly affixed to said blade and a second member attached to said first member in desired adjusted relation thereto and means normally to retain said second member in a predetermined normal operating position; said second member retaining means comprising biasing means urging said second member toward a flow reducing position and disableable counteracting restraining means for said second member.

2. A comminuted material feeding arrangement cornprising a comminuted material supporting member having an edge, means to provide a heap of comminuted material on said member to a height sutficient to cause said material freely to flow over said edge, a blade between said edge and said means in parallel relation to said edge, position adjusting means for said blade comprising a rotatable shaft coupled to said blade and operable to adjust the position of said blade into the surface of said heap between said heap providing means and said edge, a sector member alfixed to said shaft, an arm rotatably carried by said shaft adjacent said sector, means to lock said sector member to said arm in selected adjusted relative position, releasable retaining means to retain said arm in a predetermined position, and biasing means urging said arm from said predetermined position in a predetermined direction.

3. Ore feeding means for supplying a continuous freely falling blanket of comminuted ore particles comprising, an elongated lip; means to heap ore particles to be treated behind said lip to a height necessary to cause particles to cascade over said lip, said means comprising ore delivery means behind and spaced from said lip; a control blade between said ore delivery means and said lip and spaced from said ore delivery means and from said lip; and adjusting means connected to said blade operative adjust ably to position said blade into said heap; said adjusting means comprising a first member rigidly affixed to said blade and a second member attached to said first member in desired adjusted relation thereto and means normally to retain said second member in a predetermined normal operating position; said second member retaining means comprising biasing means urging said second member toward a flow reducing position and counteracting restraining means for said second member and manually operable disabling means for said restraining means.

4. A comminuted ore feed mechanism comprising a stationary horizontal extended lip, means to provide a pile of comminuted ore behind said lip to a height sufficient to cause said ore to cascade over said lip; a blade between said lip and said means and parallel to said lip; adjustable mounting means for positioning said blade in said pile to interrupt the upper surface thereof thereby to regulate the rate of flow of ore under said blade and over said lip in accord with the adjusted position of said blade; said mounting means comprising a sector member rigidly connected with said blade, an arm connected to said sector member in selected adjustable position relative thereto, manually disengageable arm engaging latch means for engageably retaining said arm in a predetermined position, and biasing means for said arm effective upon manual disengagement of said latch means to move said arm, said sector and said blade in a direction to reduce the rate of ore flow over said lip.

5. In an electrically exicted comminuted ore treatment machine comprising an ore treating portion adapted to receive a. continuous blanket of ore particles: an elongated lip disposed above said portion; means to heap ore particles to be treated behind said lip to a height necessary to cause particles to cascade over said lip, said means comprising ore delivery means behind and spaced from said lip; a control blade between said ore delivery means and said lip and spaced from said ore delivery means and from said lip; and adjusting means connected to said blade operative adjustably to position said blade into said heap; said adjusting means comprising a first member rigidly afiixed to said blade and a second member attached to said first member in desired adjusted relation thereto and means normally to retain said second member in a predetermined normal operating position; said retaining means comprising biasing means urging said second member toward a flow reducing position and counteracting restraining means for said second member, said restraining means being operatively responsive to the excitation condition of said machine and disabled upon reduction of said excitation.

6. In an electrically excited ore treatment machine, a comminuted ore particle feeding mechanism comprising an elongated horizontal lip, means to pile ore particles behind said lip to a height suificient to provide free cascading of said particles over said lip, an elongated blade between said means and said lip and parallel to said lip, force applying means biasing said blade downwardly into the pile of said ore particles, blade retaining means retaining said blade against said biasing force, said retaining means comprising means responsive to a reduction in said machine excitation to release said blade for actuation by said force applying means.

7. In a comminuted ore separating machine comprising electromagnetic means to provide a magnetic field and means to direct a sheet of ore particles to be separated through said field, the combination of a movable member, a gate member connected to said movable member and arranged to control the rate of flow of ore in said sheet in accord with the position of said movable member, said gate being biased toward a flow rate reducing position, and a magnetic keeper responsive to an excited condition of said electromagnetic means normally to retain said movable member in position to maintain said gate member in an increased flow rate position against said bias, said keeper being disabled upon de-excitation of said electromagnetic means.

8. In a comminuted ore separating machine comprising electromagnetic means to provide a magnetic field and means to direct a sheet of ore particles to be separated through said field, the combination of a movable member, a gate member adjustably connected to said movable member and arranged to control the rate of flow of ore in said sheet in accord with the position of said movable member, said gate being biased toward a flow rate reducing position, and a magnetic keeper responsive to an excited condition of said electromagnetic means nor mally to retain said movable member in position to maintain said gate member in an increased flow rate position against said bias, said keeper being disabled upon de-excitation of said electromagnetic means.

9. In a comminuted ore separating machine comprising electromagnetic means to provide a magnetic field and means to direct a sheet of ore particles to be separated through said field, the combination of a movable member, a gate member connected to said movable member and arranged to control the rate of flow of ore in said sheet in accord with the position of said movable member, said members being biased toward an ore flow interrupting position, and retaining means responsive to excitation of said electromagnetic means to retain said movable member against said bias in position corresponding to ore flow past said gate member, said restraining means being disabled by a predetermined reduction in intensity of said excitation to release said movable member for movement under the influence of said bias.

References Cited in the file of this patent UNITED STATES PATENTS 430,758 Smith June 24, 1890 482,419 Willford Sept. 13, 1892 1,217,613 Little Feb. 27, 1917 1,866,781 Ullrich July 12, 1932 2,245,200 Johnson June 10, 1941 2,445,501 Vagim July 20, 1948 FOREIGN PATENTS 13,845 Great Britain of 1906 319,156 Great Britain Sept. 19, 1929 

